AUSTRALIA could be on the brink of a startling underwear revolution, thanks to Gold Coast couple Jan and Chuck Digney ("just your average mum and dad") and their invention: the backless brief.

Jan had a visible G-string problem and asked her daughters for advice.

"They said they freebag it, basically, `We don't wear undies Mum."

"Well," says Jan, speaking after a champagne-fuelled lunch to celebrate the launch, "there's got to be something out there to stop people from doing that".

She worked through 50-odd prototypes before arriving at a design that replaces the back with two bra-style straps under the bottom.

"It's like freebagging but you're protected," she says.

The challenge, says Chuck, is to get people to believe they stay up.

The couple has spent $300,000 on the first run of 35,000 and patenting the invention across the world.